Nanofiber Assembly by Rotary Jet-Spinning

Abstract

High voltage electrical fields and low production rate limit electrospinning, the electrical charging of polymer liquids, as a means of nanofiber fabrication. Here, we show a facile method of fabrication of aligned 3D nanofiber structures by utilizing high speed, rotating polymer solution jets to extrude fibers. Termed rotary jet-spinning, fiber morphology, diameter and web porosity can be controlled by varying nozzle geometry, rotation speed, and polymer solution properties. We demonstrate the utility of this technique for tissue engineering by building anisotropic arrays of biodegradable polymer fibers and seeding the constructs with neonatal rat ventricular cardiomyocytes. The myocytes used the aligned fibers to orient their contractile cytoskeleton and to self-organize into a beating, multicellular tissue that mimics the laminar, anisotropic architecture of the heart muscle. This technique may prove advantageous for building uniaxially-aligned nanofiber structures for polymers which are not amenable to fabrication by electrospinning.

Forming of Polymer Nanofibers by a Pressurised Gyration Process

“…The centrifugal force accelerates the liquid stream where solvent evaporation and polymer chain elongation occurs. [ 16 ] This acceleration is enhanced by the gas blowing operation where liquid exerts more force to overcome the surface tension force. By considering the Matsui model, [ 24 ] the relationship between air drag coeffi cient ( C f ) and fi ber diameter can be obtained.…”

“…It only uses the centrifugal force in a rotary mould as rotation shears the polymer solution to form fi bers. [ 15,16 ] Indeed, it is independent of solution properties such as electrical conductivity and dielectric constant which govern electrospinning, but the process is limited by complicated spinneret design which can lead to large differences in fi ber quality and productivity. On the other hand, solution/melt blowing is a proven largescale method to form a web of polymeric fi bers.…”

Beads, beaded-fibres and fibres: Tailoring the morphology of poly(caprolactone) using pressurised gyration

“…The entanglement of polymer chain largely suppresses jet formation [20] and within a certain viscosity range, when the viscosity of polymer solution is increased up to a critical value, the fibre diameter increases as well, and the relaxation time needed for the elongation of polymer jet increases due to the incremental amounts of physical entanglement between polymer chains. Yet the polymer jet could still keep a certain shape post-stretching and finally forms bead free uniform fibre [21,22], but if the viscosity approaches and drops below the critical value, fibres with bead on string structure will be formed. Figure 3 (a-e) shows the bead size/average inter-bead distance distribution and SEM images of products generated by 5 wt%, 10 wt%, 15 wt%, 20 wt% and 25 wt% solutions at 36,000 rpm rotation speed and without the application of any pressure.…”

“…The fibre sizes measured for 5wt% and 10wt% are 3±1 µm and 23±8 µm, respectively. Literally, in a certain range of viscosity (below the critical value of PCL concentration for the formation of bead free uniform fibres), the more viscous solutions will impose a higher resistance against the destabilising centrifugal force and dynamic fluid blowing, which will promote a larger bead size, thicker fibre, and longer distance between adjacent beads [22]. The product of 5 wt% PCL solution has a more irregular morphology and larger average bead size, that is ~658µm in width and ~756 µm in length, compared with the product of 10 wt% PCL solution (~145 µm in width and ~157 µm in length).…”

Fibers for hearts: A critical review on electrospinning for cardiac tissue engineering

“…The scaffolds are incubated in solutions containing the biological substance, which coats the surface of the fibers. Fibronectin is the most widely used biological substance for cardiac cells and has been coated on chitosan [68], PCL [153] [84], PLA [154] and PU [99]. Collagen type-I was also used on P(L-D,L)LA [111] and laminin on PLGA [121].…”